Clinical trials comparing high and low oxygenation rates in ICU patients who have acute hypoxemic respiratory failure have revealed inconsistent results. A multicenter trial was conducted to determine whether a lower target for partial pressure of arterial oxygen (PaO₂) compared with a higher target would reduce 90-day mortality rates in ICU patients who had acute hypoxemic respiratory failure.

The study included a total of 2,928 adults who had been admitted to the ICU within 12 hours with hypoxemic respiratory failure and were receiving at least 10 liters of oxygen per minute in an open system or had a fraction of inspired oxygen (FiO₂) of at least 0.5 liters in a closed system. They were randomized to receive oxygen therapy targeting a PaO₂ of either 60 mmHg (lower-oxygenation group) or 90 mmHg (higher-oxygenation group) for up to 90 days.

At 90 days, 618 of the 1,441 (42.9%) patients in the lower-oxygenation group and 613 of the 1,447 (42.4%) patients in the higher-oxygenation group had died. The percentage of days patients were alive without life support or after discharge weren't significantly different between groups. The percentages of patients with one or more serious adverse events (new episodes of shock, myocardial ischemia, ischemic stroke, or intestinal ischemia) were also similar in the two groups.